Manufacture of cellular bodies



Feb. 9, 1943.

W. OWEN MANUF-ACTURE OF CELLULAR B Filed Feb. 8, 1938 ODIES 4 Sheets-Sheet 1 BY f3 Z7 Q 3 A RNEYS.

Feb. 9, W OWEN MANUFACTURE OF CELLULAR BODIES Filed Feb. 8, 1938r 4 Sheets-Sheet 3 111 Q 108 v v INVENTOR. lf/ 1.. /HM OWEN BY e A RNEYS.

Feb. 9, 1943. w, OWEN 2,310,457

MANUFACTURE OF CELLULAR BODIES Filed Feb. 8, 1958 4 Sheets-Sheet 4 s En mN m I* me m NNN Rm @w mw A E O ,www WAHI] M E EN mm m .l lllll/ L Y NNN NNN .w M

Patented Feb. 9, 1943I UNITED STATES PATENT voI-Flclz I 13 Claims.

The present invention relates to the manufacvture of cellular material suitable for use as insulating media against the -transmission of heat and as 'a `light Weight building material and it has particular relation to the manufacture of such materials from glass or glass-like substances such as blast .furnace slag.

One object of the invention is to provide aprocessof preparing highly porous or cellular bodies from glass, blast furnace slag, or similar relatively refractory but thermoplastic materials which is simple, requires relatively small expenditure of labor, which is continuous in operation and which results in a product having exceptionally satisfactory properties for use as an insulating medium against the transmission of heat andas a light weight building material.

It is well known that cellular or porous materials comprising a solid or a fibrous material containing a myriad of small interstices or cells filled with partially or completely entrapped air or other gaseous medium possess high value as insulating media against the transmission o'f heat. Among the commoner materials which have been employed for such purposes may be included brous substances such as asbestos,cel

lulose fibers, or cellular materials such as cork and the like. jNone of these materials is entirelyA satisfactory. For example, the asbestos is fairly expensive and lacks in mechanical strength.l Furthermore, it will pack down during service so that the' insulating value thereof is impaired. The organic materials are lacking in resistance to heat and lire.` Moreover, the resistance-to acids, alkalles and other chemicals is but slight.

It has heretofore been proposed to substitute for such materials slabs or blocks of material containing numerous voids or gas cells obtained by liberation of a gas in molten or plastic glass, or similar materials. Various methods have been suggested for preparing the cellular bodies. One method involves the incorporation of carbon in the form of charcoal, into molten, or at least plastic glass. This material by reason of heat and chemical action is decomposed in the glass to liberate carbon dioxide or carbon monoxide as more or less uniformly distributed bubbles. The method is objectionable because of the difficulty of obtaining satisfactory bubble distribution. Moreover, decomposition of the gassing agent before its complete incorporation into the glass often occurred. l

A second method involves subjecting relatively uid glass to vacuum whereby to liberate and expand the entrapped or absorbed gases as innumerable small bubbles distributed through the mass. A The product obtained by such method is unsatisfactory, for many purposes, because vit comprises substantially continuous bodies of vitreous glass in which the bubbles are entrapped. Usually the specific gravity of such masses is high and the insulating value is comparatively low. By reason of the dense, vitreous character of the material it is also diiiicult to cut and shape it to suitable size and form. Furthermore, the methods as heretofore proposed are intermittent in character and require a relatively large number of individual molds which must be separately lled, thus' necessitating expenditure of much time and labor.

According to the provisions of the present invention the foregoing diiliculties are substantially obviated by admixing glass or glass-like material such as blast furnace slag in a relatively nely divided condition with a gassing agent designed to be decomposed at or near the softening temperature of the glass and then depositing the resultant mixture upon or in contact with a rotating drum by means of which the material is heated to a temperature sucient to soften and sinter the particles of vitreous material together and to decompose the gassing agent, thereby expanding the sintered mass into cellular state.

For a. better understanding of the invention referencev may be. had to the accompanying drawings in which Figure 1 is a vertical cross-sectional view of a simple embodiment of apparatus suitable for use in practicing the invention.

Figure 2' is a cross-sectional view taken substantially upon the line lI-II of Figure 1.

Figure-3 is a cross-sectional view taken upon a vertical plane of a second embodiment of apparatus illustrating the invention.

Figure 4 is a cross-sectional view taken subustantially upon the line IV-IV of Figure 3.

Figure 5 is a cross-sectional view taken upon v a vertical plane of a third embodiment of apparatus which may be employed in invention.

Figure 6 is a cross-sectional view taken substantially upon line VI--VI of Figure 5. In the drawings like numerals refer to like parts throughout.

In the form of the invention illustrated in Figures 1 and 2 a furnace or heating chamber l0 practicing the of convenient form is constructed of a refrac- 'Y tory material such as firebrick or the like. vA

rotating drum II for receiving the mixture of crushed vitreous material and gassing agent is disposed in the furnace and includes a rotating tubular shaft I2 which projects through the side wallsof the furnace and is journaled in bearings I3 supported by suitable uprights I4 and I6 disposed exteriorly of the furnace. Heating uid such as combustion gases may be admitted to the shaft by means of conduit I1 which has a swivelled connection I8 at one end of the shaft. Outlets I9 in the shaft permit the escape of the heated gases to the interior of the drum I I. 'Ihe gases may escape from the drum in any conven-- ient manner. For example, they may pass out between the edges of the cylindrical member 21 and the relatively movable disks 24. The precise manner of escape of course is not a feature of the present invention.

As best shown in Figure 2, shaft I2 is encased by a sleeve 2| and spaced sleeves 22 and 23 are disposed about the latter and projects through the sides of the furnace I0. The inner extremities of these sleeves are joined to annular disks 24 which are disposed about sleeve 2I and constitute sides for drum I I.

Radial arms 26 are connected to the sleeve 2| at or adjacent the mid vportion thereof and at their outer extremities are joined to a cylinder 21 of somewhat smaller diameter than the disks 24, thereby providing a peripheral wall for the drum II. Resilient contact is maintained between the disks 24 and the edges of the cylinder 21 by means of helical springs 28 having the extremities thereof respectively engaging the ends of sleeves 22-23 and the sides of washers 29 which are disposed about the shaft I2 and the outerfaces of which engage the adjacent ends of bearings I3.

Independent driving mechanisms for the disks 24 comprise gears 3l and 32 mounted respectively upon sleeves 22 and 23 which are driven by means of pinions 33 and 34. The pinions in turn are mounted upon the shafts of motors 36 and 31 which are disposed upon bearings I3.

Cylinder 21 constituting the peripheral wall of the drum II is also independently driven with respect to the disks 24 by means of mechanism including a gear 38 mounted upon one extremity of tubular shaft I2. The gear in turn is driven by means of a pinion 39 upon the shaft of motor 4I which is disposed upon a bracket 42 upon support I6. f

A conveyor 43 preferably of chain form and comprising a heat-resistant material such as chrome steel is disposed below the drum- II in position to coact with the cylinder 21 in the formation of the cellular sheet. This conveyor is trained about suitable rollers or sprockets 44 and 46, one or both of which are driven by suitable means (not shown). The working surface of the conveyor conveniently may comprise a series of slabs or bars 41 disposed in edge -to edge contact upon the chains constituting a substantially continuous surface.

For purposes of preventing any tendency of the cellular mass while still soft and plastic to ad- 'here-to these bars a hopper 48 is disposed upon the rear wall 49 of the furnace chamber I0 and has a downwardly a`nd inwardly-inclined chute 5I, the lower extremity of which terminates A mixture of crushed glass, slag or otherl vitreous material and a gassing agent such as crushed calcium carbonate are fed between the surface of the cylinder 21 and the upper reach of conveyor 43 by means of a vertically disposed chamber or chute 52, the lower extremity 53 of which constitutes a shoe-like member and curves involutely inwardly between the cylinder 21 and the adjacent reach of the conveyor 43.

Chute 52 is supported by means of plates 55 which are pivoted upon a shaft 56 which extends transversely of the chamber I0 in such manner as to permit a slight rotation of the plates in order to permit the lower extremity of the chute to be swung toward or away from the surface of the cylinder 21. Adjustment of the position of the chute is obtained by means of a bolt 51 which is secured at one extremity to the chute 4and the other extremity extends through an opening in a column 58 at the rear of the furnace III. The bolt is held in any desired position of adjustment by means of nuts 59 and 6I threaded thereupon.

Crushed material comprising the batch is fed to the chute'52 by means of an intermediate chamber 62, the throat 63 of which connects to the upper extremity of the chute and which is closed or regulated by means of conventional mechanism such as slide valve 64. The upper throat 66 of the intermediate chamber opens into a hopper 61 and the passage between the two is also closed by means of a slide valve 68.

- Thebatch may be fed to the hopper 61 manually adjacent to the upper reach of the conveyor 43.

or by means of a suitable chute 69 which extends to a storage bin or chamber (not shown).

For purposes of externally heating the lower portion 53 of the chute 52 and the conveyor 43 suitable heating elements may be provided. In the form shown these elements comprise tubes 1I which extend transversely through the side walls of the furnace I0 and may be employed either as tuyres for the admission of combustible gases, or may be employed as radiant tubes through which heated combustion gases are fed. Any convenient electrical heating units may also be substituted for or employed in combination with these tubes. Exhaust gases are vn'thdrawn from the furnace by means of a stack 12, leading away from the upper portion thereof.

Stripper mechanism for removing any cellular material which may tend to adhere to the cylinder 21 maybe provided and in the form shown comprises a member 13 of wedge shape, which preferably is hollow for purposes of admitting cooling fluid, which is circulated through the hollow member by means of lconduits 14 and 16. Member 13 is supported upon the inner extremities of arms 11 which'are journaled upon brackets 18 secured to the external surface of the forward wall 'I9 of heating chamber I0. Arms 11 are also provided ,with a rearwardly projecting portion 8I on which is disposed a counterweight 82 which functions to urge the members 13 into contact with the cylinder 21. By suitable adjustment of the position of the counterweight any desired degree of pressure between the member 13 and the cylinder may be obtained. 'A

An opening 83 is formed in the lower portion of wall 19 and the rear portion of conveyor 43 extends therethrough in proximity to arfriction plate 84 which preferably is hollow and is`prpvided with conduits 86 and 81 for the admission of cooling fluid. A sizing roller 8B also coacts with the portion of the conveyor which is external of the heating chamber and functions to maintain uniform thickness of the cellular sheet as it is formed. The cellular material after passing over the plate 84 passes through an opening 89 in a rear chamber 9| and is carried -by a series of rollers 92 through the latter. In its travel the sheet passes under a series of tuyre tubes 93 which function to direct ames of progressively decreasing intensity toward or against of 28 mesh per inch, while it is practically oompletely retained by a screen of 100 mesh. Usually if material of either larger or smaller particle size are employed the results are not satisfactory.

However, for some purposes the use of such sizes may be desirable.

'I'he material may be fed into the hopper either cold or preheated to a temperature of, for'example 1000 or 1200u F.

Calcium carbonate constitutes the most satisfactory gassing agent thus far employed, because'it decomposes to liberate its chemically The cellular mass as it is formed is carried by the conveyor 43 under the member 13 and the sizing roll 88 which function to compress and spread it to desired thickness.` In the space between the furnace or chamber |0 and the leer 9| the' cellular mass cools down to such extent that it looses most of its plasticity. Preferably it is cooled approximately to 1100" F. and about which temperature annealing begins. The sheet is passed through the annealing leer and is cooled down over a period which may be as much as four or -i'lve hours in such manner thatthe strains therein are relieved so that the finished product is sumciently stable for handling and use.

The sheet or strip is finally cut into blocks of suitable proportions. The finished product as -previously stated is highly cellular and seems to be composed of minute particles which are sintered together at the points of contact Without complete fusion into each other.4 Therefore, the masses comprise many uniformly distributed bubbles, the walls of which themselves probably include many vsmall voids or air spaces which function to increase the insulating value othe material. Also, by reasonof the structure, it can easily be sawed or cut and may be annealed and', pierced without shattering. The'masses are of excellent insulating value for heat. They are combined gases at a temperature of about 1500 F. This temperature is slightly above that of incipient fusing or sintering of the particles of crushed glass, but is below that at ,which the particles are completely fused together to form a homogenuous mass. Preferably the temperature of the sheet upon the conveyor 43 is raised to about 1600 or 1650 F. and below that of complete fusion (about 1700 or 1750 F.) of the crushed glass.

The sintered or more or less vplastic mass -is expanded by decomposition of the 'calcium carbonate to a degree which of course will depend somewhat upon the amount of calcium carbonate employed. Usually about 1 or 2 per cent of the latter are used and the optimum seems to` be about 11/2 per cent. Within the latter range the mass is expanded about 7 to 10 times its initial volume and the finished product will have a weight of about 14 or 15 pounds per cubic foot. The formation of masses of greater or less density by the process is of course contemplated. For example, the material may have a weight'pf 10 to 75 pounds or even more or less per cubic foot.

The heating of the material may be lso regulated that the gassing agent decomposes at any predetermined point of contactwith the drum 21. However, if decomposition occurs at or near the point lof closest approach of the drum to conveyor 43, greater room for expansion of the material as it travels forward will be afforded and there be less tendency to compress and distort the structure of the cellular mass. It is also possible so to regulate the rate of vheating that the mass between the drum and the conveyor that the particles will merely sinter together at about 1400 or 1500 F. to form 'a coherent butv unexpanded sheet. Subsequently while the sheet is upon the also light of weight and chemically and fireresistant to an exceptional degree. Furthermore, they do not tend to pack down into dense masses during service.

The independent drives for the cylinder 21 and discs 24 may be employed to impart relative movement to these members, in event that the material tends to adhere thereto. By speeding up or retarding some of the parts with respect to the others the adhesions are broken.

In the form of the invention disclosed in Figvures 3 and 4 a furnace or heating chamber |00 is provided, and includes front and rear walls |0|. |02, side walls |03 and top wall |04. -Mechanism for forming the cellular sheet o l strip includes a cylinder |06 carried by arms |01 conveyor 43 the temperature is raised to 1600 or 1650 F. to plasticize the mass and to decompose the calcium carbonate, thereby forming the cellu` lar sheet.

which radiate from a sleeve |08. The sleeve in f turn surrounds-a tubular shaft |09 which projects through the side Walls |03 of the chamber |00 ani is provided with closed ends |l|, the ends being provided with swivelly connected conduits H2 through which a cooling medium for the shaft is circulated. The shaft at its extremities is journaled in bearings ||3 formed in uprights ||4, disposed exteriorly of the chamber |00 at the sides thereof. Upon one extremity of the sleeve |08- is disposed a gear H6 which mates with a pinion |1 upon the shaft I8 ci motor |9 which is mounted upon any convenient support and which constitutes '-a source of power fordriving the drum |06.

Batch material is fed upon the drum |06 .by apparatus whichincludes a columnar supply chamber |2|, the lower extremity of which opens downwardly in proximity to the upper portion of the drum |06. Throat |22 at the upper extremity of the chamber |2| opens into an intermediate chamber |23, the passageway between the chamber |23 and throat |22 being regulated by means of a suitable slide valve |24. Intermediate chamber |23 in turn is fed bymeans of a hopper |26 joined thereto and the throat |21 of which is closed at will by means of slide valve |28. Crushed batch material in turn is fed to vitreous material inthe chamber |2| and upon the surface of the drum |06 is supplied from any convenient source. In the drawings are shown conduits |3| which may be employed either as tuyres or as radiant tubes through which hot combustion gases are conducted. Waste gases from the chamber may be conducted away by means of ue |32 having a butterfly valve |33 constituting a damper, disposed therein.

Obviously heated gases circulate freely through the openends of the drum and heat, the latter from Within.

It will be observed that the forward wall of the column |2| terminates slightly'above the surface of the drum |06, thus providing a slot |34 through which the material forming the cellular sheet |36 is fed. A sizing roller |31 is disposed adjacent to the opening |34 in position to contact with and smooth out the sheet of material as itis drawn outwardly through the slot |34. The shaft |38 of this-roller extends through the side walls |03 of chamber |00 and at the extremities is journaled in upwardly extending portions |39 of uprights I I4. The shaft also has a gear |'4I keyed thereupon and driven by a train comprising meshing gears H5, |42 and |43 journaled upon stu-b shafts |44 projecting `in Wardly from the members |39. Gear |43 in turn n mates with and is driven b y gear ||'6 already described.

Mechanism for positively stripping the cellu lar sheetaway from the roller |31 and preliminarily chilling the upper surface thereof comprises a hollow bar |46 having a wedge-like forward edge |41 which tangentially contacts with the surface of the roller |31. Conduits |48 are also connected to member |46 and constitute means for circulating a cooling uid therethrough. Member |46 is supported uponthe free extremities of arms |49, which are secured to a shaft |5 I, and which in turn is journaled in bearings in brackets |52 integrally formed with or otherwise secured to the side walls of chamber |00. An arm |53 also projects rearwardly from the shaft |5| and counterweight |54v is adjust-'- ably mounted thereupon in such manner as to admit of regulation of the pressure between the member |46 and the roller |31.

The freshly formed sheet of cellular material is strippedv away from ythe drum |06 by means of a slip plate |55 having a knife-like forward edge |56 which tangentially contacts with the surface of the drum. The slip plate is of hollow construction and is connected vby means of conduits |51 with a suitable source of cooling fluid (not shown). The cellular sheet on the plate |55 is propelled forwardly at uniform rate by meansof rollers |58 preferably of hollow construction for the admission of cooling fluid, the rollers being journaled in bearings and driven by motors (not shown).

The cellular sheet is carried away from -the plate by means of rollers |59 and while still highly heated may be cooled by blasts of air from conduits |6|, that are disposed above and below the sheet at suitable intervals, to cool the sheet down approximately to the annealing temperature. e. g., 1100 F. For purposes of annealing the sheet the conveyor system comprising rollers |59 is extended through an vopening |62 in a leer |63 provided with suitable means such as burnsintering together the particles of glass or other' the internal strains in the sheet of cellular ina-- terial are relieved.

A further form of the invention as illustrated in Figures 5 and 6 comprises uprights |14 disposed at the corners of a furnace |15 having a roof consisting of twin arches |16.

Mechanism for forming the cellular sheet includes slightly spaced parallel drums |11 and |13 mounted upon hollow shafts |19 and |8| and each partially enclosed by one of the arches |16. The drums are heated by means of combustible gas mixtures supplied through conduit |82 (see Fig. 6), which extends axially of shafts |19 and |8| and are provided at their inner extremities with spider-like manifolds |83, the arms of which extend through the walls of the shafts |19 and |8|. The combustion gases may be permitted to escape from the drums in any convenient manner. For example, ports or openings |85 may be formed in the sides of the latter to permit the gases to escape into the furnace where they are carried away by the stack. The shafts are also cooled by suitable means, a tube |84 leading to a suitable source or cooling iiuid and being journaled in the end wall |86 of the shaft. A tube |81 of substantially less diameter than the tube |84 is nested in the latter and projects forwardly into the shafts |19 or |8| a substantial distance for the removal of uid from the shafts.

Shafts |19' and |8| are journaled in bearings |9| supported upon cross beams |92 upon uprights |14. The shafts are also provided with sprockets |93 and |94 and a sprocket chain |95 is trained about the latter sprocket and one reach thereof contacts with the former sprocket. The sprocket chain is further trained about a driving sprocket |91 upon the shaft of a motor |98 by means of which these drums are driven in synchronism. The motor in turn is supported by Vbracket |99 upon upright |14.

Heat may be supplied to material disposed upon the drum by means of such devices as tuyres ,200 which project through the sides of the furnace |15 in proximity to the surface of the drums.

vCrushed batch material such as a mixture of relatively finely divided glass and calcium car- `bonate may be fed upon the drums by suitable lustrated these mechanisms comprise hoppers leer as to obtain gradual cooling action whereby 202 mounted upon supports 203 which are car- -ried by a cross beam 204 upon intermediate portions of uprights |14. The hoppers at their lower extremities discharge into horizontal chutes 205 which may bei of so-called syntron type and operated by means of a suitable electrical device (not shown). The horizontal chutes in turn discharge into vertical chutes 206, which at their lower extremities terminate adjacent to the surfaces of the drums |11 and 18. One of the chutes is so disposed as tn discharge directly into the bank or bight between the drums.

Uprights |14 at their upper extremities are provided with an additional set of cross beams 201 which support a hopper or storage bin 208 of relatively large proportions. This hopper at its lower extremity is provided with a swinging chute 209 which may be employed selectively to ll any of the hoppers 20| with batch material.

Batch material after passing between thev drums |11 and |18 is held in contactwith the latter over a substantial period of time by means of a slip shoe 2H whose center-curvature as shown in the drawings coincide with that of the drum |18 or which may be so curved as to permit expansion of the material in a radial direction with respect to the axis of the drum as the gases are liberated by decomposition jof gassing agent. By proper proportioning of the parts the mass may be allowed to expand with but slight restricshoe 2|| may be supported by any convenient means, for example by means of bracket,2|2.

The cellular sheet 2|3 is stripped away from drum |18 by a wedge-like'bar 2|4 which is shown tionfrom the lparts in contact therewith. The v cellular material, a shoe curved about a portion as a hollow construction for the admission of y cooling uid. The bar is supported upon arms 2|6, hinged at 2|1 to uprights |14 and further provided with rearwardly-extending portions 2|8, upon which are supported counterweights 2|9.

The cellular sheet is-carried away from the forming rollers |11, |18 by means of a conveyor system comprising rollers 22| and extending through opening 222 in the forward wall 223 of leer 224 which corresponds -to leer 9| or |63. In

this leer Ithe rate of cooling of the cellular sheet is so regulated as to relieve the strains therein.

The mode of operation of this embodiment of the invention closely corresponds to that already described, except that the material is deposited upon the surfaces of the conveyors in a plurality of thin films. In this embodiment of the invention the first of the vibratory feeder mechanisms may be employed to deposit a preliminary lm of nely divided sand or other highly heat-resistant material upon the surface of the drums in order to prevent possible adhesion, of the cellular sheet thereto. The remainder Vof the feeder devices may then be employed for depositing a suitable mixture of crushed glass, crushed blast furnace slag or other material upon the surfaces of .the drums.

It will be apparent that the material is deposited in successive thin layers thus obviatingthe necessity of transmitting heat through thick masses of pulverized material. The layers readily bond together into a unitary whole. -Heating of the material may be so eiected that liberation of the gases to form bubbles occurs prior to passage of the material between the two rollers. However, it is also possible to operate so that the material does not expand until it has passed between the rollers and is between roller or drum |18 and shoe 2| When the apparatus is so operated, it may be of advantage to curve the shoe 2|| so that the space between it and drum or Y roller |18 progressively increases.

The forms of the invention lherein shown and described are to be considered merely as exemplary and it will be apparent to those skilled in the art that numerous modifications may be made therein without departure from the spirit 0f the invention or the scope of the appended claims. 'l

What I claim is:

1. Apparatus for forming cellular sheets by sinteringa mixture of crushed vitreous material and a gassing agentdecomposable by heat to lliberate a gas whereby to form cells in the sintered mixture, comprising a heating chamber, a rotatable drum disposed in the chamber, means for depositing a relatively uniform layer of the mixture of crushed vitreous material and gassing agent upon the drum, vand means for heating the of the drum in spaced relation thereto and extending into proximity at itslower end to the conveyor system, means for feeding a relatively uniform layer of a mixture of crushed vitreous material and a gassing agent between the drum and the curved shoe and means for heating the interior of the drum to sinter the glass while it is in contact with the drum and to decompose the gassing agent.

3. Apparatus as defined in claim 2 which further comprises a wedge-like stripping member contacting with the surface of the drum for purposes of removing the freshly formed sheet from the drum.

material upon the drum in` contact with the lower portion thereof, and means for continuously feeding a mixture of crushed vitreous material and a gassing agent between the drum and the conveyor and means to heat the 'mixture while it is in contact with the drum to sinter the glass andto decompose the gassing agent.

5. Apparatus as-defined in claim 4 in which means is further provided for preliminarily depositing a thin layer of pulverulent heat-resistant material upon the conveyor to prevent adhesion of the cellular sheet thereto.

6. Apparatus as defined in claim 4 in which the means for feeding the mixture of crushed vitreous material and gassing agent comprises a shoe curved aboutthe drum in spaced relation -thereto and terminating at-its lower extremity adjacent to the surface of the conveyor.

7. Apparatus as dened in claim 4 in which the means for feeding the mixture of crushed vitreous material and gassing agent comprises a supply chamber disposed approximately at one side of the drum and having one wall terminating at the surface of the drum and having the opposite wall curved about the drum in spaced relation thereto and terminating at the surface of the chain conveyor.

8. Apparatus for continuously forming a sheet of cellular material by the sintering of fa. mixture of a crushed vitreous material and a gassing agent comprising a heat chamber, a pair of parallel horizontal drums disposed in the chamber, means for rotating the drums'in opposite directions, means for feeding a-,mixture of'crushed vitreous material as a relatively uniform layer upon each of the drums, said drums being so disposed that as they rotate the layers upon the drumsA are pressed together -to form a unitary sheet.

9. Apparatus as defined in claim 8 in which feeding means is provided for directly depositing additional crushed material between the bight of the drums.

10. Apparatus as defined in claim 8 in which a shoe is curved about one of the drums in spaced relation thereto for purposes of holding the material upon the drum in contact therewith after it has passed through the bight of the drums.

11. Apparatus for forming cellular material by sintering a mixture of crushed vitreous material and a gassing agent, comprising a drum consisting of a cylinder mounted upon a rotatable axle, a pair of annular discs slidably and rotatably mounted upon the axle, means urging the discs into contact with the edges of the cylinder, means for driving the cylinder and the discs independently of each other, means to supply crushed vitreous material and a gassing agent to the drum and means to heat the material upon the drum.

12. Apparatus for forming a continuous sheet of cellular glass from a mixture of crushed glass and anagent decomposable by heat to form a gas, said apparatus comprising arotatable drum, means to feed said mixture into contact therewith, means to maintain such contact over a substantial arc of the drum, means to heat the interior of the drum to bring the material while on the drum to the sintering point of the glass and to the decomposition temperature of the agent, whereby to form a coherent cellulated sheet, and means to strip the sheet away from the drum as it is formed.

13. Apparatus for forming cellular sheets by sintering a mixture of crushed vitreous material and a gassing agent decomposable by heat to liberate a gas, whereby to form cells in the sintered mixture, comprising a heating chamber, a rotatable drum disposed in the chamber, means for depositing a layer of the mixture of vitreous material and gassing agent inl contact with the drum, and means for heating the interior of the drum to bring the mixture to the sintering point of the crushed vitreous material and to decompose the gassing agent while the mixture is upon the drum, and a wedge-like stripping member disposed to contact with the surface of the drum for removing the cellular sheet therefrom.

WILLIAM OWEN. 

